The present invention relates to a mixing arrangement for mixing a substance for the field of dentistry, the production of which substance requires at least one base material and one reactant. The present invention also relates to a method for mixing such a substance, particularly for mixing an adhesive,. wherein the substance is produced from a base material and a reactant that are mixed together immediately prior to the substance being used.
Such a mixing arrangement is known from DE-OS 3 733 799. In this known solution a base is provided, the base comprising color basins in which coloring matter can be mixed. A plurality of color basins are provided next to each other in order to make it possible to compare the coloration achieved.
Numerous additional mixing arrangements comprising bases have become known in which either a component of a mixture is maintained and stored on the base in advance and an additional component is added at the time of application or in which both or, if applicable, all (i.e., more than one) components are mixed together on the base at the time of application.
Such bases can be flat or essentially basin-shaped in order to facilitate removal and the mixing process itself. The known mixing arrangements use bases in which the components to be mixed are applied in succession. The bases can be basin-shaped (see, e.g., DE-OS 3 733 799) or even flat, the mixing then being performed by means of a spatula or another suitable application element.
It has been suggested that the base be embodied as a disposable base, e.g., made of an economical plastic sheet, or made from a more substantial material, in which case the surface of the base can then as a rule be wiped off and cleaned well. Solid and re-usable bases are very economical in terms of material consumption in dental laboratories and dental practices. However, they require a certain amount of care during cleaning to prevent residual matter from the previous mixture from leaving contaminants. Apart from this, a re-usable base as a rule cannot be used for all substances mixed in the field of dentistry, particularly small amounts of substances whose proportions to each other are precisely regulated (e.g., adhesives).
Furthermore, it has already been suggested that a so-called single dose unit be prefabricated and that the dentist have available a prefabricated and packaged unit comprising the substances to be mixed, the application element, and the base, if any. The best solution in terms of packaging and manufacturing costs would be to produce a blister package that comprises the various openings for the substances and, e.g., even for the application element. However, if one of the substances to be mixed is a liquid, for instance, this solution is hardly practical because combining the individual substances that are each applied to the same base requires that the blister base be cut to permit additions to be made in the manner desired. This type of mixing however would necessarily be awkward and prone to contamination so that it has little market value, at least to this point in time.
Experienced dental technicians and dentists frequently favor containers that have been pre-filled with the substances to be mixed over single dose units. Although such solutions regularly require less complex packaging, the complexity of metering is greater, especially when it is important that mixing ratios be maintained. Pipettes and droppers that can handle small quantities have become known for liquids. Metering apparatus have also become known for powder substances, although these are frequently associated with high costs because a metering apparatus that is used for different substances must be cleaned after every process in which a substance is added in, and this would not be acceptable for a dental practice.
On the other hand, it is very important, particularly when using catalysts as reaction substances, that they be present in an active form (i.e., in a form in which a reaction cannot be triggered prematurely or when this is not desiredxe2x80x94a reaction that substantially affects quality and safety when using an adhesive, for example), that the required reaction substances be combined in the defined ratio and in undiminished quality.
The object of the invention is therefore to create a mixing arrangement of the aforementioned general type and furthermore to create a method that combines the advantages of providing the substances to be mixed from containers and the advantages of a single-dose unit.
The mixing arrangement of the present invention is characterized primarily in that a catalyst is applied to a base surface as reactant in a solid or semi-solid layer and the unit comprising catalyst and base is prefabricated, and in that the base material, particularly in liquid form, can be applied or introduced to the base surface that is provided with the catalyst prior to using the substance, and in that the substance can be applied ready for use by means of an application element after the catalyst and the base material have been mixed.
In accordance with the invention, one of the substances required for the reaction, particularly a base material can be stored and maintained in a container, e.g., a bottle. Both the base and at least one other reaction substance, particularly a catalyst, can be provided in a type of single-dose unit, the special advantages in accordance with the invention resulting in that the reactant is already provided on the base so that there are no concerns about spillage when the reactant is applied to the base nor is awkward handling required for the single-dose unit. On the contrary, a basin in the blister base can be provided with the base material at once, e.g., in the form of a drop, and then the mixing required can be performed directly and on-site using the necessary application element.
This eliminates complex metering of the reactant, and, depending on the state of aggregation of the base substance in the particularly advantageous inventive embodiment, filling the basin can be used as an indicator for adding the base material. If, for instance, a solid or semi-solid catalyst is applied to the base and the base is basin-shaped, the metering can be coordinated such that to achieve the desired mixing ratio it is possible to fill the basin up to the border line of the reactant layer drawn up the side face. If, on the other hand, the reactant applied to the base is semi-solid and a liquid substance is to be introduced as the base substance, it is also possible to provide the application element with a metering basin like a type of spoon that permits measuring without the use of any specially embodied metering apparatus.
In accordance with a particularly advantageous embodiment of the inventive mixing arrangement, it is provided that the catalyst or the other reactant is prefabricated in a closed container as a single-dose unit. This solution ensures that the more sensitive of the substances is maintained until it is used, particularly under an air seal, so that even for extended periods of storage there is no reason to be concerned about a diminution in the quality of the substances required for the reaction.
Nevertheless, the base substance can be added from a container, e.g., a bottle. For instance, one or more drops can be added from a bottle with adhesive to the basin in which the catalyst film is located and the catalyst is dissolved and incorporated.
In this context it is particularly advantageous that in accordance with the invention even the form of the solid reactant can be adapted to the mixing ratio and the base substances available. An appropriate predetermined volume is established for the basin and used as the base for the inventive mixing arrangement.
In this context it is particularly advantageous when the targeted degree of filling relative to the entire system is at least 20%, comprising reactant or reactants and base material. A degree of filling that approaches approximately 50% contributes to improving the thoroughness of mixing (given an equal number and intensity of the stirring strokes), it being understood that in accordance with the invention it is preferred that a solid or semi-solid substance is mixed with at least a semi-liquid substance, preferably a liquid substance.
As a rule, it is advantageous when the basin comprises radii at the transition between the side faces and bottom surface in order to improve the thoroughness of mixing. The radii are preferably dimensioned such that they fit the nose radius of the enclosed application element in order to simplify handling.
This solution is particularly useful in the advantageous embodiment of the mixing arrangement that provides in the basin in one packaging unit both the accessory application element in a compartment and the base that is already provided with the reactant.
It is to be understood that the shape of the basin, particularly the height/width ratio, can be adapted to requirements in many fields. Thus the basin can be embodied as a base surface that is flat, slightly concave, or highly concave. The basin can be covered with a sealing foil or a plurality of basins can be covered with one foil that can be pulled off by individual basin, if necessary.
In a particularly advantageous embodiment of the inventive mixing arrangement it is provided that the basin and the compartment are covered and sealed by a common sealing foil that can then be removed in one pull. This embodiment is particularly suitable for employment in a safe and simple manner. The user pulls the sealing foil off and removes the application element from the compartment. The base material is added to the reactant up to the specified marking and stirred briefly with the application element. Then the finished substance is applied to a surface by means of the application element. Such surfaces are, e.g., dental cavities, the surfaces of teeth, root canals, but such surfaces can also be technical dental restorations like crowns. Once the treatment has concluded, the application element can be replaced in the compartment and the basin can be resealed by pressing the sealing back onto it. In this manner the mixing arrangement can be disposed of with no contamination, even if there is still residual mixed, finished substance remaining in the basin. Required for this solution is the realization of re-closable packaging, e.g., blister packages. Appropriate heat-sealable media are known in and of themselves.
The invention is particularly important for light-curing and dual-curing (light- and self-curing) dentin protectors, cements, or adhesives such as are employed, e.g., in filling technology for composites or for cementing crowns. When using these materials, three catalysts are necessary (e-g., camphorquinone for light-curing, peroxide and amine for self-curing). Since these three catalysts cannot be stored in one material, the only option is to mix together two (if not three) liquids or pastes before the material is employed for its purpose. Using the present invention it is possible to store in one basin one or two catalysts as solid or semisolid substances in a surface coating and to produce, e.g., a dual-hardening adhesive by adding a liquid that contains an additional catalyst.